What term describes America250’s 250th-anniversary milestone?

America250’s 250th-anniversary milestone is called a semiquincentennial.

The word combines “semi-,” meaning half, with “quincentennial,” meaning a 500th anniversary. A semiquincentennial is therefore a 250th anniversary, or half of a millennium. The term is less familiar than “bicentennial,” which describes a 200th anniversary.

The United States used “United States Semiquincentennial” as the formal historical name for the 2026 observance, while “America250” served as its branding. “Quarter-millennium” is another understandable description, but it is not the event’s standard name.

The terminology connects the 2026 celebration with earlier national milestones. The 1976 United States Bicentennial marked 200 years, while the 1926 observance was associated with the 150th anniversary, or sesquicentennial, of independence.